60D + telescope: problems

I am liking my 60D, but having a problem when I attach it to a telescope with a T-ring. (I have done this before with my old Rebel XT with moderate success.) In fact there are two problems. I have been trying to take moon shots, setting the camera to manual mode, and selecting the lowest ISO (100). If I try to use live view, the shutter speed setting that produces a reasonable preview in live view gives a greatly overexposed shot. The focusing (set manually on the telesccope) is also very hard to get right. I can get around the overexposure by lining up something that looks reasonable in live view, the switching off live view and upping the shutter speed. But that doesn't help with the focusing. I was hoping that live view would be a big advantage (the XT doesn't have this), but so far it's not working out too well. (I hope all of that is clear.) Any suggestions for getting better results?